If you want to tinker with tiny lenses, you might want to Google electrowetting lens and check out those articles.

Leon

02-09-2012, 04:21 PM

Some years ago someone was working on spectacles for third-world countries that used flexible water-filled lenses. Water could be pumped into them for a wide range of adjustment.

skylight

02-09-2012, 08:04 PM

I remember those specs Leon, did you see the "contact" lenses that Philip Schofield tested on the "Good Morning" programme a little while back, instead of wearing the contact lenses during the day you put them on during the nights sleep and they compress the lens of your eyeball and so adjust the focus, he said they worked extremely well and he could see perfectly(may have been a plug I don't know) but apparently the indent in the eye lasts for the whole day and you just repeat the process at night time.

Leon

02-09-2012, 08:21 PM

No, I didn't see those contact lenses.

I've always been short-sighted but I've never worn contact lenses. A friend of mine severely damaged his sight with them.

skylight

02-09-2012, 08:25 PM

What happened, have heard some stories of welders having accidents whilst wearing contacts but not sure if they are true or not

Humanoido

02-10-2012, 07:33 AM

Perhaps the human eye has electrowetting characteristics or it could be introduced to adjust eye focus without glasses. ElectricAye, those are some great sources for this project.

Gadgetman

02-10-2012, 08:52 AM

Pinhole imaging is an interesting topic.
In fact, a lot of people experience it every day, they just don't realise it.
(Sometimes, when you're out in the rain and blink your eyes you see microscopic particles for just an instant. Then a drop was caught in just the perfect position in your eyelashes)

with a bit of practice, it's possible to use a piece of aluminium foil with a pinprick as an enlarger, but it takes practice and good light.
and that's the problem with pinhole imaging, you need lots of light.
My Holga 120W pinhole camera has a F135 rated pinhole, and with my regular 100 film, it takes 7 - 9 seconds to properly expose a single image in bright daylight.
Get a GOOD F200 pinhole, and well...
In theory, the most perfect lens you could make would be a 1 atom wide hole in a 1 atom thick film, but then you're already getting problems with quantuum physics.
(And also the fact that photons tends to act weirdly whenever they feel like it)
Yes, the thickness of the film the hole is made in matters. You want a hole, not a tunnell.
Todays pinhole cameras use thin aluminium foil or mylar film, not paper or cardboard as the earlier types.
(Incidentally, the first disposable cameras were pinhole designs. A glass platen, with paper bellows stuck to it, and a taped over pinhole at the front. Take a picture, put the tape back over the pinhole, mail the whole thing to the processing lab, wait... wait... get a picture in the mail)

In theory, the most perfect lens you could make would be a 1 atom wide hole in a 1 atom thick film, but then you're already getting problems with quantuum physics.

This doesn't seem right to me. If by "lens", you mean pinhole, then if the hole is too small, you'll get problems with diffraction. The optimal hole size is dependent on the wavelength of light you wish to capture and the distance from the hole to the film. For camera sizes one would normally use, and wavelengths around 550nm, this works out to be between a fifth of a millimeter and a third of a millimeter (or about the size of a pinhole).

Gadgetman

02-10-2012, 11:42 AM

Maybe I'm a bit off... about 550nm or so... (Not a clue as to the real size of an atom)
The thickness of the material, though, really is important.

Humanoido

02-10-2012, 03:24 PM

I think I've reached holes small enough to qualify for diffraction effects and need to measure their diameters but don't want to invest in expensive equipment.

Humanoido

02-10-2012, 03:30 PM

Just a single pinhole will make a good telescope for viewing the sun, large sunspots, and solar eclipses. You can get free holes like this using a large tree with lots of leaves that arrange in a semi occluding Fibonacci series. Just look at the ground or the tree's shadow to see some good formed solar images. Usually around eclipse time someone comes up with a photo of these crescent shapes projected on the side of a house or the ground.

ElectricAye

02-10-2012, 03:41 PM

I think I've reached holes small enough to qualify for diffraction effects and need to measure their diameters but don't want to invest in expensive equipment.

There's a physical relationship between the diffraction patterns, wavelength, and size of pinhole. Perhaps you can measure these diffraction rings if you have a laser or some kind of monochromatic light???